CN1170775C - Membrane-integrated hydrothermal reaction ultrafine nano-titanium dioxide production method - Google Patents

Abstract

The invention relates to a production method of superfine titanium dioxide by membrane integrated hydrothermal reaction. Titanium compound solution with certain concentration generates titanium dioxide suspension after hydrothermal reaction, feed liquid is added with deionized water and is continuously sent into a tubular membrane separation device for separation and washing, water and dissolved inorganic ions flow out through membrane pores and are discharged, titanium dioxide is intercepted in a membrane tube and flows out from an outlet of the membrane tube, the titanium dioxide returns to be circularly separated, the materials are repeatedly washed, separated and concentrated in continuous circulation until the concentration of the inorganic ions in discharged liquid is reduced to a set requirement, the deionized water is stopped being added, and then the materials are further separated and concentrated to obtain ultrafine titanium dioxide suspension or a titanium dioxide ultrafine powder product with the average particle size ranging from 2 nanometers to 10 micrometers is obtained through a drying procedure.

Description

Film-integration hydrothermal reaction superfine nano titanium dioxide production method

(one) invention field

The present invention relates to the production method of titanium dioxide ultra-fine nano-powder.

(two) technical background

The technology of preparing of ultra-fine nano-powder more and more is subject to people's attention as the substance of nanosecond science and technology.The titanium dioxide ultra-fine nano-powder has purposes very widely in many fields such as ceramic, photochemical catalysis, coating, its preparation method is the focus of studying in the powder preparing technology always.Along with the development of nanosecond science and technology, higher requirement is proposed also nano-powder.Effective control of granule-morphology, size, crystal formation, purity is the universal demand of high quality nano powder preparation.At present, industrial production nano titanium oxide generally is to carry out with non-pressurized sulfuric acid process, by forming metatitanic acid, obtains the titanium dioxide powder product through technologies such as washing, calcining, classifications.Titanium dioxide has the mixing crystal formation of rutile-type, Detitanium-ore-type and brookite type and the first two kind.The conversion of complete, the crystal formation of realizing that lattice grows, metatitanic acid need be through the calcination process of high-temperature very.Because high-temperature calcination often brings particulate to grow up and reunites, the titanium dioxide powder particle grain size and the pattern of this method production can not be well controlled, and monodispersity is bad.

The Hydrothermal Preparation nano TiO 2 powder is considered to more promising a kind of method.Water-heat process has quickened ionic reaction and has promoted hydrolysis, and a step is finished the lattice forming process.Though the Hydrothermal Preparation research of titanium dioxide both at home and abroad has relevant paper report, industrialized production method fails to set up.Its major cause, the one, after hydro-thermal reaction is finished titanium oxide nanoparticles be difficult to separating of foreign ion to solve, traditional separate mode such as centrifugation, press filtration etc. can not effectively be used.Another reason be hydro-thermal reaction rule not on top of as yet.

(3) summary of the invention

The object of the invention provides a kind of film-integration hydrothermal reaction superfine nano titanium dioxide production method of suitable suitability for industrialized production, can control the particle diameter and the crystal formation of titanium dioxide well, and titanium oxide nanoparticles is separated fully with foreign ion, obtain high purity, monodisperse titanium dioxide superfine powder.

Method of the present invention is that membrane sepn and hydro-thermal reaction technology is integrated, forms complete, successive production process.

Concrete steps are as follows:

Certain density titanium compound is dropped in the hydrothermal reactor autoclave pressure, by alkali or acid for adjusting pH value, the pH scope is at 0-14, be warming up to 90-250 ℃, carried out hydro-thermal reaction 3-72 hour, generate tio_2 suspension, reaction finishes, material is cooled to behind the normal temperature to extract out continuously from reactor enters medial launder, in material, add deionized water continuously, send in the lump in the film pipe of membrane separation unit, liquid phase in the material sees through fenestra and discharges membrane separation unit, being washed also, the solid phase titanium dioxide granule of enrichment is trapped in film pipe inner suspension liquid, flow out from the outlet of film pipe, returning medial launder separates again, material in continuous working cycle by repetitive scrubbing, separate, concentrate, wherein the mineral ion of reaction generation is discharged membrane separation unit with liquid phase material, thereby tio_2 suspension purity is improved constantly, inorganic impurity ion content reaches the setting requirement in relief liquor, during for example less than 50ppm, stop to wash, material continues to stop the membrane sepn process when circulation is concentrated to reach solid content 〉=30% (weight) subsequently, gets the titania slurry product.With this suspension slurry by spraying drying or lyophilize dry median size at the titanium dioxide superfine powder of 2 nanometers in 10 micrometer ranges.Also can carry out drying by modes such as solvent component distillations.The permeable membrane of above-mentioned membrane separation unit can adopt mineral membrane or organic membrane.

The raw material titanium compound of present method is selected from compound titanium tetrachloride, titanium sulfate, sulfuric ester titanium, alkyl titanate, metatitanic acid.

The weight concentration of present method reaction feed liquid titanium compound can be at 1%-40%.

The present invention is relevant with the pH value of temperature of reaction and reaction feed liquid by the crystal formation of hydro-thermal reaction generation titanium dioxide, under certain temperature of reaction, suitably controls the pH value of feed liquid, can obtain needed crystal formation.For example be raw material, provide by following table by the crystal formation of hydro-thermal reaction generation titanium dioxide and the relation of pH value with the titanium tetrachloride:

Table 1 titanium tetrachloride hydro-thermal reaction generates the crystal formation of titanium dioxide and the relation (200 ℃ of temperature of reaction) of pH value

The pH value of reaction feed liquid	0.5～0.9	1.0～3.5	3.6～8.3
				Generate the crystal formation of titanium dioxide	Rutile-type	Rutile-anatase octahedrite mixed type	Detitanium-ore-type

The last table pH controlling valu during for 200 ℃ of temperature of reaction, temperature of reaction difference, pH controlling valu are also different.In addition, the generation transformation efficiency of hydrothermal temperature of the present invention and titanium dioxide has confidential relation.When reaction times one timing, hydrothermal temperature high conversion more is high more.When temperature of reaction greater than 200 ℃, hydro-thermal reaction 15 hours, transformation efficiency is near 100%.In addition, higher temperature of reaction helps the accelerated reaction process.

The inventive method is compared through the technology of calcining production titanium dioxide powder by forming metatitanic acid with existing, and significantly advantage is: 1. technical process is simple, does not need can realize the growth and the conversion of crystal formation through calcining, and productive rate is also high.2. water-heat process has been for reaction, crystallization provides a kind of special physicochemical environment, owing to do not need calcining, prevented from effectively that particulate from reuniting to grow up, and it is good to form the particulate monodispersity, also is convenient to morphology control.3. membrane separation unit and hydro-thermal reaction device is integrated, form the serialization production process, little titanium dioxide granule to 1-2nm is realized effectively holding back, and the washing of finishing simultaneously foreign ion separates, both improved the yield of product, improved the purity of product again, the quality of product improves greatly.4. the form of product can directly be a suspension and do not need also can obtain powder through super-dry through disperseing.These all are that existing titanium dioxide production method institute is irrealizable.

(four) description of drawings

Fig. 1 is a film-integration hydrothermal reaction superfine nano titanium dioxide technological process of production block diagram of the present invention.

Fig. 2 is the relation curve of hydro-thermal reaction productive rate and temperature of reaction.

As shown in Figure 1, the raw material titanium compound drops in the reactor 1, by the acid-base accommodation material liquid pH value, reacting rear material enters medial launder and passes into membrane separation device again, deionized water is added in the material of membrane separation device, liquid phase water separates discharge through film in the material, and the suspended state material that is trapped returns the medial launder separation recycling. Material is between medial launder and membrane separation device in the iterative cycles process, constantly wash through deionized water, inorganic ions in the material is dissolved in the water discharges with water, when inorganic ions is reduced to predetermined value in the material, stop washing, continue circulation and separate and dewater, when being concentrated to solid content 〉=30% to suspended material, getting the tio_2 suspension product or send into drying program and get the titanium dioxide superfine powder.

When Fig. 2 curve represented to carry out hydro-thermal reaction take titanium tetrachloride as raw material, the reaction time was in 15 hours the situation, the titanium dioxide conversion ratio of hydro-thermal reaction and the relation of reaction temperature. Abscissa is the reaction temperature value among the figure, and ordinate is the titanium dioxide conversion data. As seen from the figure, reaction temperature is when 70 ℃ of left and right sides, and the titanium dioxide conversion ratio is about 45%, when reaction temperature is 200 ℃, and titanium dioxide conversion ratio nearly 100%.

(five) embodiment

Embodiment 1

34.72 the titanium tetrachloride of kilogram is prepared 700 premium on currency solution (weight concentration about 5%) with deionized water, the pH value of regulating this solution with sodium hydroxide is 0.85.It is in 1000 liters the hydrothermal reactor autoclave pressure that above-mentioned 700 liters of reaction feed liquids are joined volume, heat temperature raising to 200 ℃, reacted 15 hours, after reaction finishes, water flowing is cooled to room temperature with feed liquid in reacting kettle jacketing, feed the inorganic ceramic membrane separation unit again and spend the separation of ionized water continuous washing, be reduced to 50ppm when following to chloride ion content, stop washing, slurry continues circulation and is concentrated into 30% left and right sides solid content, then by spraying drying, gets 14.5 kilograms of rutile titanium dioxide powders, yield 99%, median size 23 nanometers.

Embodiment 2

139.44 the titanium tetrachloride of kilogram is mixed with 700 premium on currency solution (weight concentration about 20%) with deionized water, is 3.6 with the pH value of sodium hydrate regulator solution.It is in 1000 liters the hydrothermal reactor autoclave pressure that above-mentioned 700 liters of reaction feed liquids are joined volume, heat temperature raising to 200 ℃, reacted 15 hours, after reaction finishes, water flowing in reacting kettle jacketing, feed liquid is cooled to room temperature, feed the alumina-ceramic membrane separation unit then and spend the separation of ionized water continuous washing, treat that chloride ion content is reduced to 50ppm when following, stop washing, slip continues to be concentrated into 30% left and right sides solid content, pass through spraying drying, get about 58.2 kilograms of anatase titanium dioxide powder, yield 99%, median size 85 nanometers.

Embodiment 3

69.72 the titanium tetrachloride of kilogram is mixed with 700 premium on currency solution (being about weight concentration 10%) with deionized water, regulating the pH value with sodium hydroxid is 13.2.It is in 1000 liters the hydrothermal reactor autoclave pressure that above-mentioned 700 liters of reaction feed liquids are joined volume, heat temperature raising to 250 ℃, reacted 15 hours, after reaction finishes, water flowing is cooled to room temperature with feed liquid in reacting kettle jacketing, feed the inorganic ceramic membrane separation unit again and spend the separation of ionized water continuous washing, treat that chloride ion content drops to 50ppm when following, stop washing, feed liquid continues to concentrate in the circulation of mineral membrane device, reaches at 30% o'clock to solid content, pass through spraying drying, get about 29 kilograms of brookite type titanium dioxide powder, yield 99%, median size 110 nanometers.

Claims (4)

1. Membrane-integrated hydrothermal reaction ultra-fine nano-titanium dioxide production method is characterized in that membrane separation and hydrothermal reaction are integrated to form a complete flow device. The continuous production process steps are as follows: Put the titanium compound with a weight concentration of 1-40% into the hydrothermal reactor autoclave, adjust the pH value to 0-14, raise the temperature to 90-250°C, carry out the hydrothermal reaction for 3-72 hours, and generate a titanium dioxide suspension, and the reaction is completed After the material is cooled to normal temperature, it is continuously drawn out from the reaction kettle into the middle tank, and deionized water is continuously added and sent to the membrane tube of the membrane separation device. The liquid phase in the material passes through the membrane hole and is discharged from the membrane separation device, and is trapped in the membrane tube The solid-phase titanium dioxide solid-phase suspended material flows out from the outlet of the membrane tube, and returns to the middle tank for circulation and separation. The material completes the repeated washing, separation, and concentration processes through continuous circulation, and the inorganic impurity ions in it are discharged from the membrane separation device along with the liquid phase material until the impurities When the ion content reaches below the set concentration, the washing is stopped, and then the material continues to circulate and concentrate until the weight solid content is ≥ 30%, and the membrane separation process is terminated to obtain a titanium dioxide slurry product with a particle size of 2 nanometers to 10 microns, the said titanium compound It is selected from titanium tetrachloride, titanium sulfate, titanium sulfate, alkyl titanate, metatitanic acid. 2. The production method of membrane-integrated hydrothermal reaction ultra-fine nano-titanium dioxide according to claim 1, characterized in that the ultra-fine nano-titanium dioxide slurry is dried to obtain ultra-fine nano-titanium dioxide powder. 3. The method for producing membrane-integrated hydrothermal reaction ultrafine nano-titanium dioxide according to claim 2, characterized in that the drying of the suspension slurry adopts one of spray drying, freeze drying or azeotropic distillation. 4. The membrane-integrated hydrothermal reaction ultrafine nano-titanium dioxide production method according to claim 1 or 2, characterized in that the permeable membrane used in the membrane separation device is an inorganic membrane or an organic membrane.

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